Aik Is Involved In Arabidopsis K Absorption Experimental Evidence

Potassium is one of the essential mineral nutrient in the cytoplasm of plant and plays a key role in plant growth and development. In China, potassium deficiency in soil is a limiting factor for crop product. The shortage of potash fertilizer has become one of the important factors restricting the development of the agricultural production in China. Thus, using genetic engineering and traditional breeding methods to increase potassium utilization efficiency in plant are promising ways to overcome the contradiction between potash fertilizer supply and demand.In this study, model plant Arabidopsis thanlina was used as the experimental material. By the end of 2000, the genome sequence of Arabidopsis was announced, thus the research on Arabidopsis gene cloning, structure and function make more progress. Arabidopsis is the first higher plant that the complete genome sequence is clear, so starting with Arabidopsis is an important avenue to study higher plant genome.AIK is a member of a multiple transporter family AtKUP/HAK/KT, that were first identified in Escherichia coli, and named KUP (K~+ uptake permeases) (Schroeder et al., 1994).In Arabidopsis, the large family called AtKUP, AtHAK, or AtKT (K~+ transporter), with 13 members. In this study, the phenotype was examined among the wild type, knockout mutant (aik) and AIK overexpressing lines, overexpressing lines showed smaller shoot and lighter weight than wild-type and mutant. Wild-type, mutant and AIK overexpressing lines were examined for potassium-nutrition characters such as K~+ content and K~+ uptake rate (under both high and low external K~+ condition ). The physiological evidences revealed that, compared with wild-type and mutant, the K~+ content and K~+ uptake in overexpressing lines have decreased in a larger degree. This result indicated that in a wide range of external K~+ concentration, the overexpression of AIK has a negative impact on the absorption of potassium.